Re: [Drakelist] Speaking of breaking Glass...
Wow. Yes, I had always heard the stories of that happening, but never saw one. Mine is almost hard to see, it didn't cave in the surrounding glass--just a very slight stress crack and a little inverted pimple where the hole is. Filaments still good. Sweep tubeshate em even tho they have given me excellent service thru the years. On 12/22/2011 9:19 PM, Jim Shorney wrote: On Thu, 22 Dec 2011 12:54:59 -0500, Curt wrote: It got so hot, the glass melted and a hole was sucked thru the side without breaking the rest of the tube. I saw something similar years ago in a sweep that was pulled from one of those horribly designed 11-Meter amps. The glass had been sucked inward and melted to the outside of the plate structure in one spot. It's been over 35 years ago, but I think I recall that the vacuum actually held. 73 -Jim -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime. HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Speaking of breaking Glass...
I witnessed something recently that In nearly 50 years of working with tube rigs, I had never seen. I was working on an older hybrid rig with 6JS6's in it. Had a known good set of finals and was getting unit ready to ship to a new owner. Powered it on the bench and all was good..did a cold neutralization...then reconnected filaments and powered up. Its sitting there at idle and I start hearing tink..tink...tink... like tubes getting hot. I look into the final cage and see both tubes filaments on. sits there some more..and I start smelling it HOT. Look again and one tube is bright red plate. Just as I reach and cut the power, I heard some arcing. Very strange I thought since it had all been working fine. So I open it all up and check out everything. All looks ok EXCEPT..the one tube that was bright has a small suck-hole thru the side of it. It got so hot, the glass melted and a hole was sucked thru the side without breaking the rest of the tube. YIKES So, smart fellow that I am, I'm thinking bad tube right?. Just to be sure, I double check the bias supply right at the sockets..looks ok. All else seems fine. Double checked the driver plate coupling cap since that can put b+ on the grids of the finals if it shorts..OK..it would have smoked both tubes anyway. So..bad tube.. So I put back in a back-up set of finals..about 80% on 10M pair. Power on, quick set bias V , watch plate current, all good.tink tink tink..AWE CRAPP!...power off. Same tube position is COOKING hot. What the So..smart fellow that I am, I plug in the bad tube and check the resistance between the tube pin above the socket to the bias bus...OPEN! Unbelievable...the grid pin connection in the tube socket had been opened up to the point that it no longer contacted the pin on the tube. Wide open throttle on one tube...even in standbyso no indication on the multi-purpose, plate meter. Quick correction of the socket...a quick look at all the empty shelf space where the expensive spare finals used to be stored...and the rig is ready to ship.. Life is an expedition... Happy Holidays and controlled bias to all. Curt KU8L ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Speaking of breaking Glass...
On 2011-12-22, at 12:54 PM, Curt wrote: All looks ok EXCEPT..the one tube that was bright has a small suck-hole thru the side of it. It got so hot, the glass melted and a hole was sucked thru the side without breaking the rest of the tube. YIKES Hi Curt, That happened to me one time here, too, only the circumstances were a bit different... I had a brand new pair of 811A tubes in my 500-watt amplifier, had just purchased a Yaesu FT-980. I got so enamoured with my being able to ...raise the average talk power of my SSB signal by virtue of the new rig's speech processor that after about 5, or so, DX QSOs on 20-meters, the fuse in the amp's power supply popped. I replaced it with a new one, and again, it blew... So I took off the amplifier's covert examined the new tubes...and lo behold, there was a tiny pin hole in the envelope of one. I guess my speech processor raised the plate dissipation of those jugs as well as my ...average talk power, to the point that the one tube got so hot the glass had softened, the vacuum was sucked out! I've never used a speech processor since that time. ~73~ de Eddy VE3CUI - VE3XZ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Speaking of breaking Glass...
- Original Message - From: Eddy Swynar deswy...@xplornet.ca To: Curt cptc...@flash.net Cc: drakelist@zerobeat.net Sent: Thursday, December 22, 2011 10:08 AM Subject: Re: [Drakelist] Speaking of breaking Glass... On 2011-12-22, at 12:54 PM, Curt wrote: All looks ok EXCEPT..the one tube that was bright has a small suck-hole thru the side of it. It got so hot, the glass melted and a hole was sucked thru the side without breaking the rest of the tube. YIKES Hi Curt, That happened to me one time here, too, only the circumstances were a bit different... I had a brand new pair of 811A tubes in my 500-watt amplifier, had just purchased a Yaesu FT-980. I got so enamoured with my being able to ...raise the average talk power of my SSB signal by virtue of the new rig's speech processor that after about 5, or so, DX QSOs on 20-meters, the fuse in the amp's power supply popped. I replaced it with a new one, and again, it blew... So I took off the amplifier's covert examined the new tubes...and lo behold, there was a tiny pin hole in the envelope of one. I guess my speech processor raised the plate dissipation of those jugs as well as my ...average talk power, to the point that the one tube got so hot the glass had softened, the vacuum was sucked out! I've never used a speech processor since that time. ~73~ de Eddy VE3CUI - VE3XZ Eimac featured this effect when they began selling ceramic tubes. They showed a picture of a glass tube with a suck-hole in the side and a ceramic operated under the same conditions that did not. I think they said the suck hole was the result of electron bombardment of the tube at high frequencies but its possible that any inclusion or weak spot in the glass could do it. I've had tubes crack from overheating but have never had a suck-out. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Speaking of breaking Glass...
Couldn't have happened to something with 6146's - would have not been expensive enough ;-) At least you found it. That's when stuff starts getting expensive. A lot of times, when an SB-220 would get a parasitic, that grid choke would get zorched. By the time that choke opened up, the grid was usually a goner and would short to the plate. I'd always have to sacrifice one 30 ohm resistor to test and make sure the tube was truly now just a lamp base and have to say that it was 100% of the time. Lots of controversy about AG6K and his suppressors. I've talked to the guy at length and he's not making a killing on those kits. He's very self-assured, but the stuff I've read tells me that he has reason to be. I saw loads of SB-220's with fried chokes, pitted tuning caps, fried relays and bandswitches and knew these were not all due to cockpit error. I even did a TL-922 with that kit once. You think the Heath parts were expensive... W1ES -Original Message- From: Curt cptc...@flash.net Sent: Dec 22, 2011 12:54 PM To: drakelist@zerobeat.net Subject: [Drakelist] Speaking of breaking Glass... I witnessed something recently that In nearly 50 years of working with tube rigs, I had never seen. I was working on an older hybrid rig with 6JS6's in it. Had a known good set of finals and was getting unit ready to ship to a new owner. Powered it on the bench and all was good..did a cold neutralization...then reconnected filaments and powered up. Its sitting there at idle and I start hearing tink..tink...tink... like tubes getting hot. I look into the final cage and see both tubes filaments on. sits there some more..and I start smelling it HOT. Look again and one tube is bright red plate. Just as I reach and cut the power, I heard some arcing. Very strange I thought since it had all been working fine. So I open it all up and check out everything. All looks ok EXCEPT..the one tube that was bright has a small suck-hole thru the side of it. It got so hot, the glass melted and a hole was sucked thru the side without breaking the rest of the tube. YIKES So, smart fellow that I am, I'm thinking bad tube right?. Just to be sure, I double check the bias supply right at the sockets..looks ok. All else seems fine. Double checked the driver plate coupling cap since that can put b+ on the grids of the finals if it shorts..OK..it would have smoked both tubes anyway. So..bad tube.. So I put back in a back-up set of finals..about 80% on 10M pair. Power on, quick set bias V , watch plate current, all good.tink tink tink..AWE CRAPP!...power off. Same tube position is COOKING hot. What the So..smart fellow that I am, I plug in the bad tube and check the resistance between the tube pin above the socket to the bias bus...OPEN! Unbelievable...the grid pin connection in the tube socket had been opened up to the point that it no longer contacted the pin on the tube. Wide open throttle on one tube...even in standbyso no indication on the multi-purpose, plate meter. Quick correction of the socket...a quick look at all the empty shelf space where the expensive spare finals used to be stored...and the rig is ready to ship.. Life is an expedition... Happy Holidays and controlled bias to all. Curt KU8L ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Speaking of breaking Glass...
Have never experienced this and hope I never do. These sweep tubes are getting too precious. 3-500's have much thicker glass than even 811A's, so I don't think it would be very easy to get a suck-out on one of those puppies. I have seen the grid get shorted to the plate - usually as a result of an initial parasitic oscillation in the tube. I've repaired lots of SB-220's and the problem is fairly common in them. I've never heard of an L-4 or L-4B failing like this... Steve, W1ES/4 -Original Message- From: Richard Knoppow 1oldle...@ix.netcom.com Sent: Dec 22, 2011 1:26 PM To: Eddy Swynar deswy...@xplornet.ca, Curt cptc...@flash.net Cc: drakelist@zerobeat.net Subject: Re: [Drakelist] Speaking of breaking Glass... - Original Message - From: Eddy Swynar deswy...@xplornet.ca To: Curt cptc...@flash.net Cc: drakelist@zerobeat.net Sent: Thursday, December 22, 2011 10:08 AM Subject: Re: [Drakelist] Speaking of breaking Glass... On 2011-12-22, at 12:54 PM, Curt wrote: All looks ok EXCEPT..the one tube that was bright has a small suck-hole thru the side of it. It got so hot, the glass melted and a hole was sucked thru the side without breaking the rest of the tube. YIKES Hi Curt, That happened to me one time here, too, only the circumstances were a bit different... I had a brand new pair of 811A tubes in my 500-watt amplifier, had just purchased a Yaesu FT-980. I got so enamoured with my being able to ...raise the average talk power of my SSB signal by virtue of the new rig's speech processor that after about 5, or so, DX QSOs on 20-meters, the fuse in the amp's power supply popped. I replaced it with a new one, and again, it blew... So I took off the amplifier's covert examined the new tubes...and lo behold, there was a tiny pin hole in the envelope of one. I guess my speech processor raised the plate dissipation of those jugs as well as my ...average talk power, to the point that the one tube got so hot the glass had softened, the vacuum was sucked out! I've never used a speech processor since that time. ~73~ de Eddy VE3CUI - VE3XZ Eimac featured this effect when they began selling ceramic tubes. They showed a picture of a glass tube with a suck-hole in the side and a ceramic operated under the same conditions that did not. I think they said the suck hole was the result of electron bombardment of the tube at high frequencies but its possible that any inclusion or weak spot in the glass could do it. I've had tubes crack from overheating but have never had a suck-out. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Speaking of breaking Glass...
On Thu, 22 Dec 2011 12:54:59 -0500, Curt wrote: It got so hot, the glass melted and a hole was sucked thru the side without breaking the rest of the tube. I saw something similar years ago in a sweep that was pulled from one of those horribly designed 11-Meter amps. The glass had been sucked inward and melted to the outside of the plate structure in one spot. It's been over 35 years ago, but I think I recall that the vacuum actually held. 73 -Jim -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime. HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
